differential change

G2 Axle and Gear makes good gears as well. Sold by 4 Wheel Parts.

Truetrac differentials ; Amazing what I can learn on these forums.

I've never heard of Truetrac Differentials. What makes them so unique? Why are they better and worth that extra cost?

Mine was around $1750 IIRC (4x4 )

klr650goldwing wrote:
Man, I've never even come close to 15.5 on the highway. The best ever has been in the 12s.

So, on a related topic would anyone be willing to share how much the swap cost you? As I understand it this swap takes a bit of mechanical precision. Does that mean that the mechanic ought to have done this job before. Or could a reasonably gifted mechanic do the first time he tried?

Thanks

It runs $800-$1200 per axle depending on what upgrades you do at the time and if other parts are needed (i.e. brakes). It is not a DIY job. I'll work on just about anything under the hood, but I don't want to screw up a diff.

Mine was ~$3,000 for both differentials at a local transmission shop.
But I also added Truetrac differentials at $500ea (and well worth it)

Man, I've never even come close to 15.5 on the highway. The best ever has been in the 12s.

So, on a related topic would anyone be willing to share how much the swap cost you? As I understand it this swap takes a bit of mechanical precision. Does that mean that the mechanic ought to have done this job before. Or could a reasonably gifted mechanic do the first time he tried?

Thanks

I went from 3.73 to 4.30 in my 5.4L-equipped 2008 F250 (read: crew cab 4x4 = heavy truck with a small block gas motor) and the difference was immediate and obvious.

In line with carringb's experience, I lost a bit of freeway economy but my around-town MPG actually ticked up slightly so for my usage there was no real "penalty" to the swap.

In many cases I feel gear swaps are overkill- especially if running a modern 6 speed auto with deep first & second gears- but I think the Ford 5.4L V8 & 6.8L V10 are exceptions to the rule.

The power's there, but you have to enable yourself to go get it...deeper gears accomplish that.

tim and amy wrote:

Also, you should not be running 89 octane in that engine, it will detonate very bad. "PLEASE NOTE, Depends if using Ethanol blend or not". On the west coast 89 octane is not good on the V10 when placed under a load.

I run 87 octane, and I even have a pretty aggressive fuel/spark map installed. As long as its top-tier fuel I don't have a problem. Its hit and miss with the cheap or no-name brands so I'll spring for 89 octane in that case, when I'm towing.

klr650goldwing wrote:
Bryan,

Did you MPG go up or down while towing after you switched to 4.56? Have you pulled that rig over the Rockies?

Thanks for your input everyone. This is very helpful information.

Solo fuel economy went from 15.5 MPG hwy to 14. Towing (~12,000 pounds) went from 6.5 to 8. Since I tow more than I don't, it was a net gain for me! For somebody who only tows occasionally, it may not make as much sense.

I tow over the Rockies at least once a year, load weight averages about 15,000 pounds but has been as high as 18,000 (trailer weight plus passengers and cargo in van), which puts my typical combined weight around 22,000 pounds but it can hit 25,000.

In the mountains, having 4.56 gears is a HUGE improvement, and that's why Ford rates their powertrains so much higher with those gears (22,000 with 4.56 vs 15,0000 with 3.73). With 3.73 gears, I couldn't even stay in overdive with a headwind, and gentle grades would drop me into 2nd. Pulling a 7% grade used to require 1st gear when I was pulling 15,000 pounds! That meant top speed was only about 35 MPH. Now I can pull the same hill and do 60 or better because I can stay in 2nd.

Some things with the Excursion V10 and gearing. I agree that you would be better off with 4.30 or 4.56's.
The V10 with 3.73 in the rockies will have dead spot, really bad when pulling a 6% grade. I find it is a very dangerous undertaking in that regard.
The V10 is a Cammer engine so it likes the RPM's, towing will hit the dead spot in the gearing.
Also, you should not be running 89 octane in that engine, it will detonate very bad. "PLEASE NOTE, Depends if using Ethanol blend or not". On the west coast 89 octane is not good on the V10 when placed under a load. The engine will detonate activating the knock sensor which will then retard ignition thus decreasing power.
The 4 cents or even 10 cents per gallon difference over a 40 gallon tank isn't worth blowing a hole through the piston.
Also, with premium the MPG's will increase by 2mpg even towing.
My v10 around town with winter blend premium Costco gas was 12mpg and 17hwy, 3.73 gears. Towing 8.8K pound trailer was 9mpg. When I did run regular it was 7mpg.